Characterizing full-phase chlorine species emissions from domestic coal combustion in China: implications for significant impacts on air pollution and ozone-layer depletion

Abstract

The distribution and emission characteristics of chlorine in different phases are important for evaluating the impact of chlorine chemistry on the stratospheric and tropospheric environment. This study developed a measurement method of full-phase chlorine and firstly reported full-phase chlorine emissions characteristics of domestic coal combustion. The chlorine content of bituminous coal is 252.5 μg/g, with 87% released into the gaseous, and the concentrations of particulate chloride (pCl), hydrogen chloride (HCl), chlorine gas (Cl₂), and organic chlorides (Cl-VOCs) of 0.57±0.16, 5.96±1.05, 0.38±0.06, and 0.03±0.01 mg Cl/m³, respectively. In addition, unexpectedly high concentrations of very short-lived substances (VSLS), such as CH₃Cl, CH₂Cl₂, C₂H₅Cl, C₂H₃Cl, and C₂H₂Cl₂, and ozone-depleting substances (ODS), such as chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), were measured, with concentration of 270.71 ppb in total. Total emission of chlorine from domestic coal combustion was 33.51 tons in 2013 and declines to 18.47 tons in 2021 in China. Our results indicate that the emissions of CFC-11-eq and CO₂-eq were relatively low compared with those of other species controlled by the Montreal Protocol on Substances that Deplete the Ozone Layer; however, subsequent controls should give greater consideration to coal combustion because of its widespread sources.